Odd Snap on Tool Box

[snapmom]

This one stumps me.  Has what is usually a late 20s tag.  Size 16 x 8-1/2 x 3.  Socket slot, what the heck fits into it.  the only thing I can find are some of the stubby deep wells from 30-31.  they are 2-3/4 to 2-1/2 in height.  where the normal deeps from that era are about 3-1/4.  I got this box with no tools, its not shown in any cats I have seen. 
Any help would be good,  I am looking for some of the 30-31 semi deeps, so holler at me if you have any.

[The Magic Ratchet]

There 2 sets, #98 and #99 in the 1929 and 1931 catalogs that look like a similar box but came with standard depth sockets. Don't know if that helps but I thought it might be a possible lead. Deep sockets seemed to be very limited in that period.

Lou Manglass